Pump for hydraulic jack systems



Nov. 19, 1940. C. A. POTTS .PUMP FOR HYDRAULIC JACK SYSTEMS Filed Oct. 8, 1957 2 Sheets-Sheet l Nov. 19,v 1940. C. A. POTTS l PUMP FORIHYDRAULIC JACK SYSTEMS `Filed Oct. 8, 1957 2 Sheets-Sheet 2 Patented Nov. 19, 1940 UNITED STATES PATENT. OFFICE 1 Claim.

This invention relates to hydraulic jack systems and more particularly to hydraulic jack systems for multiwheeled motor vehicles in which an individual jack is provided on Athe vehicle adjacent each wheel for lifting the same.

An object of my invention is to provide an improved hydraulic jack system for motor vehicles, in which a pressure fluid supply means and individual jacks associated with the respective wheels enable the driver of the vehicle to lift any one of the Wheels When it becomes necessary or desirable and to accomplish this purpose with comparative ease and without leaving the driving station.

Another object of my invention is to provide an improved hydraulic jack system, of the type mentioned, in which a manually operable pump or fluid actuator provides a supply of pressure iiuid, and valve means controlled by the driver directs the pressure fluid to any one of the jacks for raising the corresponding wheel of the vehicle and permits the release of the uid pressure into a reservoir when such wheel is to be lowered.

Still another object of my invention is to provide an improved hydraulic jack system, of the type referred to, in which each jack has ytelescoping low pressure and high pressure pistons adapted to be projected in succession in response to different pressure values of the motive fluid and a pump for supplying the motive uid has high pressure and low pressure plungers selectively operable for providing such different pressure values.

A further object of my invention is to provide a novel form of hydraulic jack having pistons of different areas adapted to be projected in succession in response to fluid pressure acting thereagainst and also having springs acting against the respective pistons to resist outward movement thereof and of which'the spring engaging the larger piston is relatively stiffer.

Yet another object of my invention is to provide a novel hydraulic jack having telescoping pistons and in which a check valve isvadapted to trap uid in one of the cylinders to prevent retraction of the corresponding piston until the other piston has been retracted.

Still another object of my invention is to provide a novel pump or fluid actuator having low pressure and high pressure plungers and means providing for actuation of the low pressure plunger by movement transmitted by the high pressure plunger.

A further object of this invention is to provide (Cl. 10B- 11) a novel pump or uid actuator having selectively operable high pressure and low pressure plungers and means for shifting the pump operation from the low pressure plunger to the high pressure plunger.

The invention may be further briefly summarized as consisting of certain novel combinations and arrangements of parts hereinafter described and particularly set out in the appended claim,

In the accompanying sheets of drawings,

Fig. 1 is a so-called phantom View showing the application of my hydraulic jack system to a motor vehicle;

Fig. 2 is a perspective view illustrating the mounting of one of the jacks on a structural part of the vehicle;

Fig. 3 is a vertical sectional view taken through the jack;

Fig. 4 is a vertical sectional view taken through the lower end of the jack and showing the same on a somewhat larger scale than Fig. 3;

Fig. 5 is a similar vertical sectional View taken through the upper end of the jack;

Fig. 6 is an elevational view looking toward the instrument panel of the vehicle from the driving seat or station;

Fig. 7 isa longitudinal sectional view taken through the pump or fluid actuator;

Fig. 8 is another longitudinal sectional view taken through the pump, but showing the plungers in elevation and occupying a different relative position than in Fig. 7, and

Fig. 9 is an expanded perspective: View showing the pump plungers` and the various parts thereof.

More detailed reference will now be made to the accompanying drawings in which I show one embodiment of my hydraulic jack system,` but before proceeding with such detailed description it should be understood that the drawings are to be regarded as being mainly illustrative and that the invention may be embodied in various other similar systems and can be applied to various types of automobiles and other vehicles.

In Fig. 1 of the drawings I show, in broken lines, an automobile l to which my improved hydraulic jack system has been applied. The automobile has the usual drivers seat or station therein and has a pair of frontvvheels Il and a pair of rear wheels I2. My improved jack system, as applied to the vehicle I0, has front jacks I4 and l5 which are mounted on the frame o-n Opposite sides of the vehicle so that each serves iov one of the front wheels II and a pair of rear jacks I6 and I1 also mounted on the frame on opposite sides of the vehicle so that each serves l one of the rear wheels I2.

rIvhis jack system also includes a fluid actuator I8, hereinafter referred to as a pump, which is mounted on the vehicle adjacent the drivers station and which has an actuating member or `pedal I9 adapted to be operated by the driver while he is occupying the drivers seat or station. A reservoir 20 located at an elevation above the pump has a supply conduit 2| leading to the latter, and a discharge conduit 22 connected with the pump leads to a control valve device 23. Check valves 24 an'd 25 provided respectively in the conduits 2| and 22, permit a flow of fluid from the reservoir to the pump and from the pump to the valve device 23 but prevent a return flow in the reverse direction.

The valve device 23 may be a manifold or `other suitable device of this character located on or adjacent the instrument panel 26 of the vehicle and having individual valves 28, 29, 30

' and 3| which are connected respectively with the jacks I4, I5, I5 and I1 by conduits 32, 33, 34 and 35 and which control the supply of pressure fluid to the jacks. This valve device also includes a valve 35 which controls a return connection 31 leading Iback to the reservoir 2U. The 301 provided respectively with operating knobs or individual valves of the valve device 23 may be handles 28a, 29a, 35a, 3la and 36EL which project from the instrument panel 25 so as to be accessil l ble to the drivers seat or station of the vehicle. 351

When the operator wishes t lift any one of the four wheels of the vehicle, he closes the Ivalve 38 which controls the return connection to the reservoir 20 and opens the control valve for the jack which serves the wheel to be lifted.

` ing the pedal I9 to therebydeliver pressure fluid into the jack which has been selected.

The driver then operates the pump I8 bywork- The jacks I4, I5, I6 and I1 are of the type having telescoping pistons and when uid pres- `sure is forced into the desired jack its pistons i will be projected and, upon engagement of one of `the'pistons with the ground or pavement, will cause lifting 0f the corresponding wheel of the vehicle. When lthe wheel is to be lowered the driver opens the valve 36 which releases the fluid i pressure into the reservoir 20 and permits the 1drawings, I show the jack I4 mounted in this manner with the upper ends of the struts 42 connected with the upper end of the jack and `with the extensible end of the jack extending .downwardly .below the brackets 40.

It will be seen from the mounting arrangement just described that if the vehicle is standing in an uneven condition, as would be the case when one `tire is deflated, the corresponding jack will as- 1sume a relatively inclined position. When this `jack is, actuated to lift the wheel the initial lifting forceV will act on a correspondingly inclined *75,axis, rather than in a. truly vertical direction,

and this will cause some lateral deflection 01.`

springing of the relatively long struts 42. Such springing of the struts enables the jack to adjust itself and to assume a more nearly vertical position during thev lifting operation without likelihood of breaking the jack or its mounting.

In Figs. 3, 4 and 5 I show in detail my novel form of construction for the jack I4. The jack may comprise an elongated outer or main cylinder 44 having a main or high pressure piston 45 reciprocably operable therein. The upper end of the cylinder 44 is closed by an end wall or cover 46, so as to provide a chamber 4l' above the piston 45 to which fluid pressure may be supplied through the conduit 32. A second and relatively smaller elongated cylinder 48 is formed in the piston 45 and has a second or low pressure piston 49 reciprocably operable therein. The upper end of the cylinder 48 is closed by a transverse wall of the main piston 45 so as to provide a chamber 55 above the low pressure piston 49 to which pressure fluid may be supplied through an opening or passage I of the transverse wall of the main piston. Leakage of fluid past the piston 45 may be prevented by providing the same with a suitable packing 52 formed of leather or other appropriate llexiible material. Similarly, the piston 49 `may, be provided with a suitable packing 53 to prevent leakage ofiluid past thesame.

The main piston 45 has a hollow stem portion or leg 55 which forms the wall of the cylinder 48 and which is slidable in an opening of the lower cover 56 of the outer cylinder 44. Likewise, the

l high pressure piston 49 has a hollow stem or leg 51 extending downwardly therefrom and which is slidable in an opening of the cover 58 ofl the hollow leg 55. The lower end of .the leg 51 carries a foot 59 which may be in the form of a plate adapted to be pressed against the earth or pavement during the lifting operation. The foot 59 may be swivelly connected with the leg 51 by means of a ball 60 which is retained in place by the cap 5 I.

The outward or downward movement' of the low pressure piston 49 and hollow leg 51 is resisted by a compression spring G2 disposed around the hollow leg and which is adapted to retract the piston and leg when the huid pressure in the `chamber 50 is released. Outward or downward `movement of the main piston 45 and its hollow leg 55 is resisted by a compression spring 63 which is adapted to retract the piston and leg `when the pressure in the chamber 41 is released.

It will be seen from Figs. 3 and 5 of the drawings that the passage or opening 5I of the main piston 45 is controlled by a check valve 65 and that this check valve is so .constructed and arranged that it will be held open when the main piston is in its retracted position adjacent the upper end of its cylinder 44. This check valve is arranged to open intothe chamber 50V and to be closed by a spring 53 when the main piston 45 moves downwardly away'from the end wall 46 of the main cylinder. The closing of this valve by the spring 55 traps fluid in the cylinder 48 above the low pressure piston 49 so as to hold the latter piston in its outer or extended position until the main piston 45 has been retracted into the cylinder 44 by the spring 63. When the main piston 45 has been fully retracted,`the check valve 65 is opened by engagement of the upper end of the valve with the end wall 46 of the main cylinder, thereby releasing the trapped fluid and permitting the low pressure piston 49 to be retracted by its spring 62.

As briefly explained above, pressure fluid is supplied to one of the jacks by a pump I8 which is adapted to be operated manually by the driver of the vehicle. This pump, as best seen in Figs. '1 and 8, is provided with a cylinder 68 in which low pressure and high pressure plungers 69 and 10 are reciprocably operable. The cylinder of the pump may be provided with a base or frame portion 1I for mounting this device in the desired location on the vehicle. y

The low pressure plunger of the pump may comprise a head portion 12 and a sleeve portion 13 which extends outwardly toward the partial cap or retaining ring 14 of the cylinder. The head portion 12 has a central opening 15 therethrough and carries a suitable packing 16 to p revent leakage oi uid between the piston and cylinder wall. The high pressure plunger 10 may be an elongated solid body of smaller area than the low pressure plunger 69 and which is slidable in the opening 'I5 of the head portion 12 and may be sealed by the packing member 16. The outer end of the high pressure plunger 19 carries an enlargement 11 which is slidable in the cylinder 68 and also has a recess 18 into which a push rod 19 connected with the operating pedal I9 extends. 'Ihe inner end of the high pressure plunger also carries an enlargement in the form of a perforated spring seat 88 which is slidable in the cylinder 68. This spring seat may be connected with the high pressure plunger by suitable means such as the stud 8| and the nut 8Ia. A spring 82 disposed between the seat 88 and the transverse end wall 83 of the cylinder serves to return the high pressure plunger 15 after each inward or working stroke thereof. During such return of the high pressure plunger, the spring seat 89 may engage a combined packing retainer and thrust member 84 of the low pressure plunger 69 to cause return movement of the latter. The member 84 may be of frusto-conical shape and preferably extends far lenough in the direction of the axis of the low pressure plunger to prevent the seat 89 from engaging and damaging the packing 16.

The high pressure plunger 10 has an operating connection with the actuating pedal I9 and, by means now to be described, the movement thereby imparted to the high pressure plunger may be utilized to actuate the low pressure plunger 69. For this purpose I provide the sleeve portion 13 of the low pressure plunger with one or more longitudinal slots 85 and a shoulder or notch 85a, adjacent the outer end of each such slot. I also provide the enlargement 11 of the high pressure plunger with lugs 86 which are adapted to travel in the slots 85 when aligned with the latter, and to engage the shoulders 85a when relative rotation between the pistons has occurred. When the lugs 86 of the high pressure plunger engage the shoulders 85a the inward movement of the high pressure plunger also causes inward movement of the low pressure plunger 69.

To enable the lugs 86 to engage the shoulders 65a I prefer to rotate the low pressure plunger relative to the high pressure plunger and, for this purpose, I provide a bushing 88 which is rotatably retained in the outer end of the cylinder 68 by the partial cap or ring 14 and which has circumferentially spaced slots 89 adapted to receive the nger-like projections 96 of the sleeve portion of the low pressure plunger for imparting rotation to the latter. The bushing 88 may be rotated in the pump cylinder by suitable means, such as an eccentric pin 92 projecting from the bushing and a lever 93 pivoted on the vehicle adjacent the drivers seat orstation and connected with such pin by a link 94. To insure reengagement of the projections 98 in the slots 89 of the bushing 88 during the return stroke of the low pressure plunger, I may provide the sleeve portion 13 of this plunger with a substantially U-shaped guide slot or groove 95 in which a guide pin 96 carried by the cylinder 13 engages.

lTo prevent dust and water from entering the lower end of the jack through the openings of the covers 56 and 58, I may provide packing rings 91 and 98, of suitable material, which seal the cover openings. The packings 91 and 98 are preferably shaped and disposed so that they will be engaged respectively by the covers 58 and 6I when the jack is collapsed or retracted, as shown in Figs. 3 and 4.

In the operation of my improved hydraulic jack system the driver of the vehicle selectsthe wheel which is to be lifted, for example, the front wheel which is served by the jack I4,fand opens the corresponding valve 28 of the valve device 23. He then operates the pump I8 by means ofthe pedal I9 to force fluid into the chambers 41 and 59 of this jack. During the initial operation of the pump the lever 93 is set so that the lugs 86 of the high pressure plunger will engage the shoulders 85 of the low pressure plunger. This results in the high and low pressure plungers of the pump making simultaneous strokes, whereby a large volume of fluid is quickly delivered to the jack.

The fluid pressure acts against both the high pressure and low pressure pistons 45 and 49 of the jack, but outward movement of the piston 45 is prevented by its relatively stiii retracting spring 63. The relatively weaker retracting spring of the low pressure piston 49 permits the latter piston to be moved outwardly by the uid pressure, thereby projecting the hollow leg 51 and lowering the foot 59 into engagement with the ground or pavement. When the foot 59 engages the ground or pavement, further downward movement is prevented and the weight o-f the vehicle resists further operation of the pump by the driver. Thereupon the driver actuates the lever 93 to rotate the low pressure plunger of the pump so that the slots 85 will align with the lugs 86. This disconnects the low pressure plunger and shifts the operation of the pump from the low pressure plunger to the high pressure plunger.

The driver now continues to operate the pedal I9 which causes reciprocation of the high pressure plunger 18, while the low pressure plunger 69 remains stationary. This reciprocation of the high pressure plunger causes a smaller volume of uid at a relatively higher pressure to be supplied ing the lowering operation the main piston 45- re-y cedesA into the cylinder 44 and displaces :duid from the chamber 41 into the reservoir. When the piston 45 reaches the inward limit of its travel, the check valve 65 engages the end wall 46 and is opened to release the fluid trapped in the cylinder 48, whereupon the piston 49 moves into the cylinder 48 and displaces uid from the chamber 50 into the reservoir 20.

From the foregoing description and the accompanying drawings it will now be readily seen that l I have provided an improved hydraulic jack system for a multiwheeled vehicle in which the jack serving any one of the Wheels can b-e selected by the driver, and can be operated by him without need for his leaving the driving seat or station. It will be seen furthermore that in my system or for various other kinds of service, and

a novel form of pump which can also be used to advantage in my improved system or wherever an efficient and powerful fluid actuator is required.

While I have illustrated and described the apparatus of my invention in a somewhat detailed manner, it will beunderstood, of course, that I do not wish to be limited to the precise construction. and arrangement of parts herein disclosed, but regard my invention as including such changesand modieations as do not constitute a departure. vfrom the spirit of the invention and the soopeof the appended claim.

Having thus described my invention, I claim:

`In a pump, the combination of a cylinder, a

main plunger reciprocable in the cylinder and comprising a head portion having an opening therethrough and a sleeve portion having a 1ongitudinal slot and a shoulder adjacent the outer end of such slot, a relatively smaller plunger reciprocable in the cylinder by movement in said opening of the head portion of the main plunger and having a lug thereon adjacent its outer end adapted for longitudinal movement in said slot, means for actuating said smaller plunger, one of said plungers being rotatable in the cylinder to align said shoulder for engagement by said lug whereby actuation of the smaller plunger causes movement of the main plunger, and means for rotating said one plunger.

CI-IALMER A. POI'TS. 

